Line a 9 x 13 baking sheet with foil. Place sweet potato cubes on pan. Pour olive over potatoes and mix covering all cubes.
Sprinkle seat salt on potato cubes. Bake in oven for about 10 minutes until potatoes are still firm but can be pierced with a fork.
While potatoes are baking, combine brown sugar and butter. Allow to begin to melt together. Then add evaporated milk or half and half. Let mixture come to a soft boil until it forms a thick caramel sauce. Remove from heat, add vanilla.
Once potatoes have baked and sauce is done, pour over potatoes on baking sheet. Stir to cover all potato cubes. Put back in oven.
Allow to bake about 5 minutes or so until a crispy crust begins to form on potatoes, You may even want to put under the broiler for a crispier crust.